It happened that two monks of the Laughing Monkey Clan were
quarreling at such volume in the Great Hall that they had
attracted an audience.
“If I wish to know a customer’s billing address,” said the
first monk, “then Customer should have a getBillingAddress
method, just as it has getName! How can you reject the
elegance of my design?”
“Because your method silently loads the address from the
database!” countered the second. “That is not the Pattern
for Value Objects! They exist only to contain the data
fetched by a DAO. You should have an AddressDAO for querying
the Address table, fronted by a Service method. The billing
address should be obtained directly from there.”
“But we have lost the Way of Object-Orientation!” shouted
the first. “Have we come full circle back to the days of C?
Our Value Objects are little more than structs, our
stateless DAOs and Services are merely collections of
related functions, and we pass around integer IDs instead of
the objects they represent! Shall we next run about on all
fours and bay at the moon?”
Wow... a roundhouse kick right to the copy constructor.
“The Way of Enterprise Design Patterns is an advancement
towards ideal simplicity, not a regression to the
primitive!” said the second. “A domain object is not
intended to work as its namesake, any more than a picture of
a shovel is meant to dig a ditch! You must set aside
appearances and focus on purpose!”
“Purpose is inherent in the name chosen!” said the first.
“Domain objects should model the real world!”
The second monk responded with a fist to the first monk’s
stomach, doubling him up. “Tell me,” said the second monk,
“in which instance variable did I hit you?”
The first monk leapt forward and boxed his opponent’s ears.
“And here I thought those appendanges were for listening!”
said the first, as the second staggered aside in pain. “How
fortunate that I set aside appearances and discovered their
true purpose!” His gloating was cut short by an uppercut to
the jaw.
A young nun—a novice—noticed that several of the Java
masters were at the edge of the crowd, silently watching the
proceedings. She ran to them.
“The two monks will kill each other before long!” said the
novice. “Why do you not settle their dispute and tell us
which philosophy is superior?”
The masters ignored her. But the nun Zjing heard, and
whispered to the novice:
“If I were the monk who prefers the Way of Enterprise Design
Patterns, I would say that you have committed the same error
as the ditch-digger. There is a question to be settled, but
you have mistaken the purposes of those present.”
“Are you saying that the masters intend to conceal the
answer from us?” asked the novice.
“Wú,” said Zjing. “If I were the monk who prefers the Way of
Object-Orientation, I would call your attention to the
Unwritten Hierarchy, in which Master is but a subclass of
Student.”
